1. Field
The present disclosure is directed to a wireless charging apparatus. More particularly, the present disclosure is directed to a wireless charging apparatus that uses microwave power to charge a device to be charged while exposing a side of the device to be charged external to the wireless charging apparatus.
2. Introduction
Presently, mobile devices have revolutionized the way we live and have become an inseparable portion of many of our lives. Chemical batteries continue to be the default source of energy for these devices, as they have been for decades. At the dawn of the 21st century, rechargeable batteries began to overtake non rechargeable batteries in the consumer electronics market. Today, the U.S. demand for rechargeable batteries is growing twice as fast as that for non rechargeables. The most popular way of charging the rechargeable batteries is through some form of cabled connection that is attached to a power outlet. Hence, most portable electronic devices are built with connectors to allow a cabled connection for charging. These connectors occupy valuable real estate, limit the flexibility of the mobile device design, and introduce complications to the mechanical integrity of the device. Harsh environment conditions that mobile devices experience accelerate the degradation of the functionality and cosmetic look of components used for the connectors. For example, accumulation of dust and dirt in the charging connectors, broken charger connector covers, and other degradation shortens the device lifetime. Elimination of these charging connectors offers significant benefit to portable electronic device users.
Recently, wireless charging for mobile devices has been introduced to combat the above mentioned disadvantages of the cabled charging of internal rechargeable batteries. Wireless power transfer based on inductive coupling is considered as a promising way of wirelessly charging internal rechargeable batteries and has gained commercial success in the marketplace. The Wireless Power Consortium has established a standard for this technology called Qi. Systems that fall within the scope of this standard are those that use inductive coupling to provide power transfer between two planar coils, one of which is a transmitter and the other one is a receiver.
In current implementations of the Qi standard, high permeability ferrite sheets are employed to electrically separate a planar charging coil of the electronic device from metal, such as a device printed circuit board ground or the device battery. These sheets, however, introduce a thickness of somewhere between 0.5 mm to 1.0 mm into the mobile device. This is, of course, in addition to the thickness already introduced by the coils and mechanical components to keep the assembly secure. Unfortunately, despite the fact that reducing the device thickness is strongly desired, these sheets add even more thickness to the existing device thickness. In addition, there are material choice considerations that should be undertaken when inductive charging technology is used. For example, presence of metal in the coupling aperture would inhibit inductive charging of the device.
Thus, there is a need for a wireless charging apparatus that uses microwave power to charge a device to be charged.